English

Symmetric A actions on $\mathcal{A}(2)$

Algebraic Topology 2024-09-02 v1

Abstract

We describe the variety of `symmetric' left actions of the mod 2 Steenrod algebra A\mathcal{A} on its subalgebra A(2)\mathcal{A}(2). These arise as the cohomology of v2\text{v}_2 self maps Σ7ZZ\Sigma^7 Z \longrightarrow Z, as in arXiv:1608.06250 [math.AT]. There are 256256 F2\mathbb{F}_2 points in this variety, arising from 1616 such actions of Sq8Sq^8 and, for each such, 1616 actions of Sq16Sq^{16}. We describe in similar fashion the 1600 A\mathcal{A} actions on A(2)\mathcal{A}(2) found by Roth(1977) and the inclusion of the variety of symmetric actions into the variety of all actions. We also describe two related varieties of A\mathcal{A} actions, the maps between these and the behavior of Spanier-Whitehead duality on these varieties. Finally, we note that the actions which have been used in the literature correspond to the simplest choices, in which all the coordinates equal zero.

Cite

@article{arxiv.2408.16980,
  title  = {Symmetric A actions on $\mathcal{A}(2)$},
  author = {Robert R. Bruner},
  journal= {arXiv preprint arXiv:2408.16980},
  year   = {2024}
}
R2 v1 2026-06-28T18:28:21.808Z